Question

I am new to database structure and design. Currently, I am in the process of creating a course catalog that will match course description according to course name and date. I have sketched one table describing the courses, which include course_code, name and every other relevant information. Then I sketched another table linking those courses to when they will be taught.

I am missing classes that are classified as all_year. Also I am missing a way how to label the courses under a major. Since hypothetically a course can belong to several majors, putting the data from one into the other would force you to duplicate data. Any ideas how I would implement this two things to my tables design? Or suggestion in how to restructure my design. If possible please show me a query to execute in my phpmyadmin DB.

Example of table courses

id serial
course_code text
description text

Example of table course_dates

id serial
course_id serial
year date
semester 

Example of table majors

major_id int
course_id int

So a populated database could contain the following:

Table courses
id course_code description
1  INF1000     "Basic programming"
2  INF1001     "More basic programming"

Table course_dates (0 for spring 1 for fall)

id course_id year semester
1  1         2012 0
2  1         2013 1
3  2         2013 1

Answer 1

To link courses to majors – this is a one to many relationship (one course to many majors) – you want to use a linking table that has this type of structure:

 table courses_majors
 major_id int
 course_id int

Remember to index this table as well – its very important. Then you can populate it and have one course even go to many majors and many course to one major (many to many relationship).

Then you can run a join on the tables across this table:

select * from courses left join courses_majors on courses.id = courses_majors.course_id left join majors on courses_majors.majors_id = majors.id

Of course you can add a where clause, etc.

The other way is to create a table of majors:

 majors
 id int
 name varchar

Then add a major_id to your courses table – this will just give you a one to one relationship from courses to majors, but many courses can join a major.

As for Yearly, I would just add a field in the database to account for this, probably a tiny int and just make it 0 or 1.